“The reason this is important to all Americans, beyond the immediate parties to this taped conversation, is that it may well discourage clients, patients, penitents and others from confiding in their lawyers, doctors, priests and the professionals who promise them confidentiality,” he wrote.

It’s uncontested that “someone” leaked the confidential tape.

“A former judge, assigned by the presiding judge to evaluate the seized tapes, reportedly concluded that this conversation was privileged. Yet someone leaked their contents. President Trump’s current lawyer, Rudy Giuliani, then waived the privilege as to that tape. He said he never would have waived it had its existence and content not been improperly leaked,” Dershowitz explained.

“So, the question remains: Who leaked this privileged material? If it was anyone in the Trump camp, there would be no violation of confidentiality, as the privilege belongs to the client, namely Trump, who can waive it. But no one else, most especially his lawyer, may properly waive the privilege. And Giuliani has categorically denied that it was leaked by Trump or anyone on his behalf. Indeed, he has expressed outrage at the leak.”

He said Cohen is “an obvious suspect,” but the fact is “we simply do not know.”

Any judicial or prosecutorial team member would have a lot to lose, he noted.

“Cohen promised confidentiality and yet the world heard what his client confided in him,” he said. “We know he recorded the confidential conversation without the knowledge of his client. That is bad enough. Then it was deliberately leaked by someone who must have believed he or she would reap some benefit or advantage from having the public hear it.”

He said it is now necessary to find the leaker.

“It is an ethical violation, subject to serious sanctions including disbarment, for a lawyer to disclose, or cause to be disclosed, privileged conversations. And for good reason. The obligation of a lawyer not to disclose confidential information is codified in Rule 1.6 of the New York Bar. This broad rule prohibits, subject to exceptions not present in this case, any knowing disclosure of confidential information,” he said.

“The fact remains that the leak occurred, and now it is imperative that the leaker be exposed and held to account.”

Dershowitz said the judge in the case could put potential leakers under oath and ask them whether they did it.

The only failing is that “people who are willing improperly to leak confidential material may also be willing to lie about it under oath.”

But he pointed out the penalty for perjury is significant.

“What is clear is who was hurt by the leak: all Americans who rely on confidentiality – which means all of us – were hurt when the world was allowed to listen to a lawyer/client privileged conversation, that no one except the participants should ever have heard,” Dershowitz said.